Setting Up Daylight Harvesting

Daylight Harvesting is a way to save energy by utilizing natural light to offset the amount of electric light needed to meet the designed illuminance for a particular area. SimplySNAP uses an open-loop daylight harvesting design. In this design, a daylight sensor is oriented towards the natural light and away from the electric lights. A hand-held light meter will be used at commissioning time to correlate the amount of daylight seen by the installed daylight sensor to the amount of daylight at the desired worksurface so that SimplySNAP can adjust the lights properly.

What's Needed for Commissioning

Definitions

  • Designed Illuminance - the amount of light seen at the work surface solely from artificial light
  • Daylight Gain - a user provided input into the SimplySNAP UI that is a correlation of the designed illuminance, a sensor reading taken at the work surface, and the external light sensor. This value is calculated from a defined formula.
  • Fade Rate - a user provided input into the SimplySNAP UI that is the duration between lighting output values. The lighting output is on a scale of 0-255, and the fade rate is the amount of time between each interval on the scale. The fade rate unit is in deciseconds.

Configuration

  1. Create a daylight harvesting zone using the instructions outlined in Adding Zones and Scenes.

  2. Add a daylight sensor to the harvesting zone (Do not move lights into the daylight zone, yet).

  3. Expand the daylight harvesting zone in the UI.

  4. Calculate the Designed Illuminance.

    1. Turn all of the lights on in the control zone.
    2. Using your handheld meter, take a reading at the darkest part of the daylight zone. Note this value.
    3. Turn all of the lights off.
    4. Using your handheld meter, take a reading at the same location as step b. Note this value.
    5. Subtract the value from step d from the value from step b. This is your designed illuminance.
  5. Calculate the Gain Value

    1. Turn the lights on.

    2. Note the "Status" value next to the Daylight Zone Sensor in the UI. This is the Current Daylight Sensor value.

    3. Using the handheld sensor, take a reading at the darkest part of the daylight zone. This is the Current Handheld value.

    4. Using the values found in the previous steps, calculate the gain value using this formula:

      ../_images/dlh_gain_formula.png
  6. Select "Edit Zone Settings".

  7. Input the calculated Daylight Gain Value. (Integer value between 1-32767)

  8. Input the Fade Rate. 10 is a good place to start. (Integer value between 1-32767)

  9. Click Save.

  10. Click Manage Lights.

  11. Add Lights to the daylight zone.

    1. Insure that the light is only in a single daylight zone or expect strange behavior.
  12. Click Save Changes.

Additional Notes

  • At least one Daylight Harvesting Zone must be configured before you add the daylight sensor.
  • The daylight sensor needs to be installed where it isn't measuring any artificial light.
  • Increase the daylight gain to increase the electric light dimming level
  • Daylight Harvesting can work with existing behaviors
  • Daylight Harvesting will not dim the electric lights below 10%; however, other configured behaviors still can turn the lights off.